North Korean exports to China increased 10.8% to $216 million, while imports jumped 16.8% to $2.59 billion, the Seoul-based Korea International Trade Association said Thursday.

The trade deficit increased by $350 million, four times the deficit from 2016, before the U.N. imposed heavy sanctions on top North Korean exports like coal and apparel.

Clocks and watches were North Korea’s biggest export to China last year at $49 million. Parts for time pieces ranked high among its imports, and the country is believed to be assembling clocks on contract from China.

In reality, things are of course much more complicated than this. At a time when sanctions remain but we still pretty much know that China has reverted to importing certain banned items from North Korea, North Korea’s effective trade deficit cannot really be studied through official data. Likely, imports that come through and are recorded officially correspond, to some extent, to exports flowing outward under the radar.